The goal of the proposed work is to develop electrophoretic light scattering as a technique for the accurate and automatic analysis of the surface charge properties of living cells and to apply this technique to problems of biophysical and biomedical significance. In the next year of the project period, work will be concentrated in the study of the asymmetry of the surface charge of living cells. Specifically, vesicles of either normal or inverted sidedness will be prepared from human erythrocytes. These vesicles will be characterized according to their surface charge and the cell surface reactions of the interior and exterior surface of the membrane will be studied by determining the responses of the two different types of vesicles to enzymatic treatments and to chemical reagents. The results of this study will be important for the interpretation of the surface charge asymmetries which have been detected in our laboratories in the study of the endocytic and exocytic processes.